It's called contention ratios. The more people who connect the less each individual can have. Bandwidth is finite and not, as many seem to think, infinite. You may notice faster speeds at night as less are connected and slower speeds at peak times. If lots of folk are streaming the latest blockbuster you drop to next to nothing.
3 may have been selling 5g in you area but stopped as they were getting close the max number of subscribers for yoy local tower.
